As the methods for introducing organic groups (that is, organo-groups) such as an alkyl group, an aralkyl group or an aryl group or the like into silicon compounds, there is now generally employed such process wherein a Grignard reagent containing said organic group is reacted with an organo-substituted or organo-unsubstituted chlorosilane containing one to four chloro groups, thereby to produce an organo-silane containing one to four organo groups and also zero to three chloro groups. However, a bulky, secondary or tertiary hydrocarbon group likely to easily bring about a steric hindrance is not readily introducible into the said organo-substituted or organo-unsubstituted chlorosilane containing one to four chloro groups, by means of the process comprising reacting the Grignard reagent containing such bulky hydrocarbon group with said organo-substituted or organo-unsubstituted chlorosilane.
There is also known another process wherein a secondary or tertiary alkyl lithium is used, instead of such Grignard reagent, and is reacted with said organo-substituted or organo-unsubstituted chlorosilane (refer to J. Org. Chem. Vol. 43, p. 3649 (1978)).
For a process for the introduction of a secondary hydrocarbon group or a tertiary hydrocarbon group likely to easily cause the steric hindrance, onto a silicon atom of an organo-halosilane by means of the Grignard reaction, there is also known a process wherein a Grignard reagent containing a secondary or tertiary hydrocarbon group is reacted with the organo-halosilane in the presence of a catalyst comprising a copper compound or a cyanide compound or thiocyanic acid compound (refer to Japanese Patent Publication Hei-7-86115, Japanese Patent No. 2838342 and Japanese Patent No. 2854832).
Further, there is known a process for the synthesis of a dimethyl-monoalkoxy-arylsilane and a dimethyl-monoalkoxy-cyclohexylsilane, comprising reacting a dimethyl-monoalkoxy-chlorosilane with a Grignard reagent containing phenyl group, 1-naphthyl group or cyclohexyl group (refer to Zh. Obshch. Khim., 1987, 57(1), pp. 146-151 and Chemical Abstracts, Vol. 108, Par. 6072v). However, the Russian literature above-mentioned has no description of the production of a tri-organo-monoalkoxysilane containing at least two of the bulky hydrocarbon groups.
There is known an organo-hydrosilane compound having a silicon-hydrogen linkage, and there is also known a process comprising reacting such organo-hydrosilane compound with a Grignard reagent containing a tertiary hydrocarbon group (refer to Japanese Patent No. 3091992).
Further, there are many known processes for the production of tri-organo-monochlorosilanes containing a bulky hydrocarbon group. Main known processes proposed for such purpose are as follows.    (1) Process comprising reacting an organo-halosilane with a Grignard reagent in the presence of a catalyst to cause a Grignard reaction to produce a tri-organo-monochlorosilane intended, filtering the resulting reaction solution to remove therefrom the magnesium chloride deposited, and recovering the intended silane product (Japanese Patent Publication Hei-7-86115).    (2) Process according to the process (1) above, wherein the reaction solution resulting from the Grignard reaction is subjected directly to a distillation after the Grignard reaction was conducted with using a solvent made of polyalkyleneglycol dialkylether (Japanese Patent No. 2854832).    (3) Commercially available process adapted for industrial scale production, wherein the silicon-hydrogen linkage of a tri-organo-hydrosilane is chlorinated with chlorine.    (4) Process wherein the alkoxy group of a tri-organo-alkoxysilane is chlorinated with a chlorinating agent such as an acyl chloride, thionyl chloride, phosphorus trichloride, and the like.    (5) Process wherein the chlorination of a tri-organo-hydrosilane is effected by an exchange reaction between a tri-organo-hydrosilane and a chlorosilane in the presence of a catalyst (Japanese Patent No. 3131868).    (6) Process wherein a tri-organo-hydrosilane is reacted with hydrogen chloride gas in the presence of a transition metal of Group VIII or a complex thereof under anhydrous condition (Japanese Patent Prepublication Kokai Hei-6-157554).    (7) Process as described in J. Am. Chem. Soc., Vol. 68, p. 2282 (1946), wherein triethylsilanol is treated with a conc. hydrochloric acid under ice-cooling, thereby to afford triethylchlorosilane in 77% yield.    (8) Process as described in a book “Chemistry and Technology of Silicones”, Page 86, (published in 1968 by ACADEMIC PRESS), wherein a trialkylalkoxysilane is treated with hydrogen chloride gas under anhydrous condition and converted into the corresponding chlorosilane.
However, in the above process (1) according to Japanese Patent Publication Hei-7-86115, the operation for the removal by filtration of the magnesium chloride by-produced is troublesome, with needs of additional treatment of magnesium chloride. In the process (2) above according to Japanese Patent No. 2854832, the use of the special solvent is necessary, so that this process is disadvantageous commercially in view of expensive cost. In the commercial process shown in (3) above, a chlorinated solvent is required as the reaction solvent, so that there is a serious problem for the environmental protections. In the chlorination process shown in (4) above, the generation of sulfur dioxide gas and other by-products is involved and is problematic in view of the environmental protections. In the process (5) above according to Japanese Patent No. 3131868, the inevitable formation of unnecessary by-products and the use of the catalyst are disadvantageous in economical point of view.
In the above process (6) according to Japanese Patent Prepublication Kokai Hei-6-157554, the use of expensive metal catalyst is required and thus not advantageous in industrial operations. In the process (7) above according to the report of J. Am. Chem. Soc., Vol. 68, p. 2282 (1946), the silanol compound is to be treated with conc. hydrochloric acid under ice-cooling conditions, because the silanol is easily hydrolyzable and is difficult to be handled, so that the industrial practice of this process is not advantageous in economical point of view. The process (8) above according to “Chemistry and Technology of Silicones”, p. 86, where the chlorination is to be effected with hydrogen chloride gas under anhydrous conditions, is still needed to be improved upon its industrial practice in respect of the safety and the operating efficiency, due to the necessary handling of hydrogen chloride gas. In consequence, all the known processes proposed in the prior art have some unavoidable defects.
Accordingly, there is a keen demand for creating any novel industrial process for the production of organo-chlorosilanes, which is able to work more easily and simply in a commercial scale.
For the purpose of producing the organosilanes containing a secondary or tertiary alkyl group or groups, the above-mentioned prior art process as shown in J. Org. Chem., Vol. 43, p. 3649 shall require that the organo-substituted or organo-unsubstituted chlorosilane is reacted with a secondary or tertiary alkyl lithium. This prior art process cannot be suitable if it is applied on an industrial scale operation with handling of a large amount of materials, because the handlings of metallic lithium and of alkyl lithium as prepared therefrom are very dangerous.
In cases of the prior art processes as taught by Japanese Patent Publication Hei-7-86115, Japanese Patent No. 2838342 or Japanese Patent No. 2854832, these processes shall require that a Grignard reaction is carried out by using the catalyst made of a copper compound, a cyanide compound or a thiocyanate compound. In these processes, the use of highly toxic compounds as the catalyst is required, thus bringing about problems on safety. In the another prior art process shown in Japanese Patent No. 3091992, an organo-hydrosilane compound having a silicon-hydrogen linkage is used as the starting material, and this starting material is often expensive. Further, in the other process of the prior art where a trichlorosilane is to be used as the starting material, the starting material is a low boiling, inflammable substance, so that special caution is required for handling it, thus causing problems on safety and economy.
Therefore, it is now keenly required to provide any novel process for producing a tri-organo-monoalkoxysilane compound having at least two bulky hydrocarbon groups each likely to cause the steric hindrance, such as a secondary or tertiary alkyl group, which process can be operated in a facile way on industrial scale, safely and in a high yield.